In many instances, it is necessary to locate a position indicating structure with respect to a work piece which is to be milled, sanded, ground, etc. The precision and stability of the positional device is important, as is the ability to re-position the positional device.
Currently, in the glass grinding industry, a variety of edge configurations are available. These complex shapes are ground by a router-type spindle which travels around a work piece.
In current practice, a generally flat surface defining a multiplicity of parallel ribs is provided. This ribbed table is used to support a series of supports which hold, for example, a planar sheet of glass in a horizontal orientation and at an elevation over the table of about four to eight inches high. The sheets of glass are usually held onto the plurality of supports by a vacuum system which incorporates safety into its operation. Once the glass is locked down onto the supports, it will not release until the grinding spindle is shut down, and or until the motion control structure which carries the grinding motor and its grinding spindle is moved off to one side.
Since the spindle grinds from its edge, the tip of the spindle is fittable with a pin or other slender structure which can be used as a locating pin. Usually the operator will, at the beginning of work on a run of similar types of glass, locate several positional devices as dictated by the operational software of the machine. Once the machinery is apprised of where the work piece is to be located, it will positionally specify the location of positional devices, which are pneumatic piston devices which have spacers against which subsequently loaded glass work pieces will be placed.
These positional devices can be positioned using an angled device against which the spacers of the positional devices may be positioned. This is a somewhat automatic step with the machine dictating the locations and the operator responding by moving positional devices as indicated by the machine. The angled block located by the machine may be picked up from a tool bin containing other tools, and replaced once the position of the positional devices is fixed by the operator. The operator moves each positional device into place, and the control causes the angled block to move to the next location in a manner which will not bump against the positional device. In fact, using conventional positional devices, the operator will typically tighten the positional device down at the time of locating it. These locating devices use the ribs in the work table to extend through a locking bar, turn the bar perpendicular to the slotted opening, and using a screw or threaded rod lock the locating device onto the table in a position adjacent the glass work piece.
Usually this locational exercise is repeated about two or more times to make sure that the edges of the glass work piece will be properly guided into place once a run of a particular type of shaping is to occur. By using the relationship of two or more positional devices, the person loading in each new piece of glass to be processed can do it consistently.
Once the positional devices, with pistons extended upwardly are used to guide the loading of the glass onto the supports, the pistons and spacers are brought downwardly out of the way to make way for the grinding spindle to do its work. Thus the positional devices are only used for an instant, but have to be exactly located at the beginning of each run, that is at the start of a particular process performed on a particular size of glass. Each time a different setup is required, which corresponds to a different size work piece or a different application, the positional devices must be manually unlocked, the computer must use a moveable member to locate new positions, and the positional devices must be re-locked into position.
The problem with the conventional system, as outlined above, is in the time required for the operator to change the positional devices. For each new work setup, the operator must manually operate the positional devices to unlock them from their fixed position. This requires the operator to crawl or squat on or bend over the work table long enough to engage the threaded holding member, usually a bolt or threaded rod, with a hex wrench or other wrench. This is extremely time consuming, dangerous and injurious to employees. Further, the times when the machine is down for changing the position of the positional device, represents a significant cost, in accord with the saying "if the spindle isn't turning, you aren't earning."
There is the further limitation which the slotted table represents to locating the positional device at particular points with regard to the work piece. Although the positional device may be turned somewhat about the axis of the threaded rod by which it is anchored to a the slotted table, its position is limited by the location of the slots. In some shapes, it is important for the computer to specifically locate the mounted positional device, to make sure that it will be in place to bear against the next piece of glass loaded onto the machine. A system which relies on a fixed slot may not always be able to meet this goal.
Another problem encountered involves the need for a separate vacuum line which is controllable, and in addition to the vacuum lines which operate the glass supports. The supports should be easily moveable, either one at a time or as a group.
Another problem deals with the location and positioning of pressure lines onto the table. A work setup which requires 10 supports will require at least 20 separate lines going onto the table, in addition to the lines for the positional device. This can make quite a mess and is dangerous for the following reasons. The pressure lines are somewhat stiff and can "bow" upwardly and get in the way of the routing or edging tool. This would cause the line to be cut and could upset the work area. More importantly, the tangle of lines makes it much more difficult and time consuming to change the setup.
Any device or system which could reduce the number of lines would be of great help and savings. Any device which would reduce the set up time for locating the positional devices would similarly result in an improved system and significant cost savings.